• International Journal of Computer Science & Network Security
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• v.21 no.9
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• pp.11-18
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• 2021

The Proportional Integral Derivative (PID) controller is the most popular industrial controller and more than 90% process industries use this controller. During the past 50 years, numerous good tuning methods have been proposed for Single Input Single Output Systems. However, design of PI/PID controllers for multivariable processes is a challenge for the researchers. A comparative study of three PID controllers design methods has been carried-out. These methods include the DS (Direct Synthesis) method, IMC (Internal model Control) method and ETF (Effective Transfer Function) method. MIMO PID controllers are designed for a number of 2×2, 3×3 and 4×4 process models with multiple delays. The performance of the three methods has been evaluated through simulation studies in Matlab/Simulink environment. After extensive simulation studies, it is found that the Effective Transfer Function (ETF) Method produces better output responses among two methods. In this work, only decentralized methods of PID controllers have been studied and investigated.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.12
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• pp.57-64
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• 2007

There have been many researches for optimal controllers in multivariable systems, and they generally use accurate linear models of the plant dynamics. Real systems, however, contain nonlinearities and high-order dynamics that may be difficult to model using conventional techniques. Therefore, it is necessary a PID gain tuning method without explicit modeling for the multivariable plant dynamics. The PID tuning method utilizes the sign of Jacobian and gradient descent techniques to iteratively reduce the error-related objective function. This paper, especially, focuses on the role of I-controller when there is a steady state error. However, it is not easy to tune I-gain unlike P- and D-gain because I-controller is mainly operated in the steady state. Simulations for an overhead crane system with dynamic friction show that the proposed PID-LC algorithm improves controller performance, even in the steady state error.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2270-2273
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• 2003

Fuzzy logic control has been widely implemented in air conditioning and ventilation systems which has uncertainty or high robust system. Since the dynamic behaviors of the systems contain complexity and uncertainty in its parameters , several fuzzy logic controllers had been implemented to control room temperature in the field of air conditioning system. In this paper, the fuzzy logic control has been developed to control room temperature and humidity in the precision air conditioning systems. The nonlinear mathematical model was formulated using energy and continuity equations. MATLAB was used to simulate the fuzzy logic control of the multi-variable air conditioning systems. The simulation results show that fuzzy logic controller can reduce the steady-state errors of the room temperature and relative humidity in multivariable air conditioning systems. The offset are less than 0.5 degree Celsius and 3 percent in relative humidity respectively under random step disturbance in heating load and moisture load respectively

• Journal of Ocean Engineering and Technology
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• v.9 no.2
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• pp.30-40
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• 1995

In this paper, it is proposed a robust control scheme for real time control of a robot manipulator with parameter uncertainties. The focus of this paper is a new approach of multivariable control schemes for an assembly robot manipulator to achieve the accurate trajectory tracking by joint angles. The proposed control scheme consists of a multivariable feedforward controller and feedback controller. In this control scheme, the feedback controller consists of proportional-derivative type and is designed by the pole placement method. The feedforward controller uses the inverse of the linealized model of robot manipulator dynamics. This feedback controller ensures that each joint enables to track any reference trajectory. The proposed robot controller scheme has a computational efficiency.

• Journal of Ocean Engineering and Technology
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• v.8 no.2
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• pp.56-63
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• 1994

This paper presents a design method of multivariable robust servo system for tracking control system for AUV(Autonomous Underwater Vehicle). In order to obtain the basic data for the design of the tracking control system, the control algorithm is evaluated in the view of computer simulation results. The tracking control is carried out for an AUV with 2 main thrusters, 2 side thrusters and 2 thrusters for the movement to up-down direction. The results of computer simulation show that the proposed multivariable servo system design method is an efficient method for the control performance of tracking control system of AUV under severe underwater environment.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.391-394
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• 1997

A H$_{\infty}$ control techniques with roll eccentricity filter is proposed to alleviate the effect of entry thickness variation and roll eccentricity occurred in rolling stand itself of tandem cold mills. A robust controller to the disturbances is designed using H$_{\infty}$ control techniques, which can reflect the input direction of disturbances and knowledge of disturbance spectrum in the frequency domain. And, non-standard H$_{\infty}$ control problem caused by selection of weight function having poles on j.omega. axis is discussed. The evaluation for the resultant controller composed by H$_{\infty}$ synthesis is done through computer simulations. The effectiveness of the proposed method is compared to those of the conventional LQ synthesis method and a feedforward controller against roll eccentricity, which was already studied.ied.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.736-741
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• 1992

The Stewart platform is one example of a motion simulator which generates 6 DOF motion in space by 6 actuators connected in parallel. The present SISO controllers are designed to track displacement command of each actuator computed from reference 6 DOF motion of platform by Stewart platform inverse kinematics. But this type of control can't cope with external load variation, geometric configuration of motion simulator, and different dynamic behavior of 6 DOF motion. In this paper, a multivariable controller using H- optimal control theory is designed for linerized simulator model with each actuator driving force as control input and platform 6 DOF motion as measured output. Nonlinear simulation result of the H$_{\infty}$ MIMO controller is not satisfied in steady-state characteristics. But the proposed H$_{\infty}$ + PI control scheme shows acceptable performance.e.e.

• ICROS
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• v.5 no.4
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• pp.14-20
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• 1999

• International Journal of Control, Automation, and Systems
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• v.1 no.1
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• pp.1-10
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• 2003

This paper presents a high-precision magnetically levitated (maglev) stage to meet demanding motion specifications in the next-generation precision manufacturing and nanotechnology. Characterization of dynamic behaviors of such a motion stage is a crucial task. In this paper, we address the issues related to the stochastic modeling of the stage including transfer function identification, and noise/disturbance analysis and prediction. Provided are test results on precision dynamics, such as fine settling, effect of optical table oscillation, and position ripple. To deal with the dynamic coupling in the platen, we designed and implemented a multivariable linear quadratic regulator, and performed time-optimal control. We demonstrated how the performance of the current maglev stage can be improved with these analyses and experimental results. The maglev stage operates with positioning noise of 5 nm rms in $\chi$ and y, acceleration capabilities in excess of 2g(20 $m/s^2$), and closed-loop crossover frequency of 100 Hz.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.786-791
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• 2005

This paper is concerned with the examination and evaluation concerning a tuning method of multivariable PID controllers based on partial model matching on frequency domain proposed by authors from practical view point. In this case, PID controller parameters are determined by minimizing the loss function defined by the difference between frequency response of ideal model transfer function and actual frequency response on several frequency points. The purpose of the paper is to examine and evaluate the performance of the method through actual experiments of MIMO liquid level experimental process control equipment.